A policer officer hits a man with a baton as he tries to maintain order while migrants wait for trains at a temporary camp near Gevgelija, Macedonia, September 7, 2015. Several thousand migrants in Macedonia boarded trains on Sunday to travel north after spending a night in a provisional camp. Macedonia has organised trains twice a day to the north border where migrants cross into Serbia to make their way to Hungary. Since June, Macedonian authorities have said that more than 60,000 migrants have entered the country, and around 1,500 entered just in one day, mainly refugees from Syria. (Photo by Stoyan Nenov/Reuters)

An Egyptian passenger sits on the locomotive of a train as it leaves Cairo train station in Egypt, Wednesday, October 14, 2015. (Photo by Amr Nabil/AP Photo)

A model poses on Aprilia motorcycle displayed at the Indian Auto Expo in Greater Noida, on the outskirts of New Delhi, India, February 4, 2016. (Photo by Anindito Mukherjee/Reuters)

Sally Gomez drives to rescue of friend Michele Moore in flooded parking lot at Hyannis, Mass., September 9, 1969, after torrential rains of Hurricane Gerda flooded low areas of Cape Cod. Ann Davis of Osterville stands up in roof opening to lend a hand. Sally and Michele are from Centerville on the Cape. (Photo by Frank C. Curtin/AP Photo)

Ultra Orthodox Jews look at the body of an alleged Palestinian assailant in Jerusalem Saturday, December 26, 2015. According to a police spokeswoman, policemen approached a man who drew their suspicions just outside the Old City for following a pair of Jewish worshippers. Then he pulled out a knife and tried to stab one of them, officers opened fire and killed the assailant. (Photo by Mahmoud Illean/AP Photo)

A baby pangolin sits with its mother inside a cage prior to their release into the wild in Sibolangit, North Sumatra, Indonesia, Monday, April 27, 2015. The anteaters are part of dozens of live pangolins and around five tons (11,000 lbs) of pangolin meat ready to be shipped abroad confiscated in a police a raid last week. (Photo by Binsar Bakkara/AP Photo)

Runners cross the Verrazano-Narrows Bridge shortly after the start of the New York City Marathon in New York, November 2, 2014. (Photo by Lucas Jackson/Reuters)

To an outsider, their passion is at times illegal and often on the verge of life and death. But climbing rooftops of high-rise buildings and exploring abandoned facilities is in the blood of these young Muscovites. The small group calls itself “Rudex”, which stands for “roof and decay exploration”, and is akin a Western youth craze known as urbex or “urban exploration” of man-made structures. Here: Urban explorer Vad Him of Rudex team jumps whilst on a rooftop in Moscow, Russia, August 14, 2017. (Photo by Maxim Shemetov/Reuters)